Boeing said on Thursday it hired former Northrop Grumman executive Colin Miller to head its Phantom Works research arm within the company's defense business unit.

Boeing has poached an executive from defense rival Northrop Grumman to run its Phantom Works division, which oversees research efforts for its Pentagon business and is involved in bidding for U.S. government projects.

Boeing says it will be several weeks before it fully resumes building passenger planes, as factory workers return following a strike that lasted nearly two months.

Boeing received its first order after reaching a deal with striking machinists, but it still faces a difficult road ahead.

After striking for almost two months, workers will return to factory floors in the Pacific Northwest, but must ensure safety procedures are followed as it begins building 737 jetliners.